Autocrine signals control CCAAT/enhancer binding protein beta expression, localization, and activity in macrophages.
Blood
; 92(11): 4353-65, 1998 Dec 01.
Article
en En
| MEDLINE
| ID: mdl-9834242
ABSTRACT
The transcription factor CCAAT/enhancer binding protein beta (C/EBPbeta, or NF-IL6) is expressed in macrophages, where it participates in lipopolysaccharide (LPS)-mediated induction of proinflammatory cytokine genes such as interleukin-6 (IL-6) and IL-1beta. We have identified activities in conditioned medium from a macrophage tumor cell line that regulates the expression, localization, and transcriptional activity of C/EBPbeta. One factor was shown to be tumor necrosis factor- (TNF-), which increased C/EBPbeta expression by a posttranscriptional mechanism. A second activity, designated autocrine macrophage factor (AMF), elicited a change in C/EBPbeta localization from a punctate nuclear staining pattern to diffuse nuclear distribution. The punctate form of C/EBPbeta correlated with increased susceptibility of this protein to cleavage by an endogenous protease during nuclear extract preparation. Conditioned medium stimulated the ability of C/EBPbeta to transactivate a reporter gene and activated the expression of two cytokine genes that are putative targets of C/EBPbeta. These observations suggest that diffuse distribution of C/EBPbeta in the nucleus corresponds to an activated form of this protein. AMF activity could not be mimicked by an extensive set of recombinant cytokines and growth factors and therefore may represent a novel extracellular factor.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Nucleares
/
Comunicación Autocrina
/
Proteínas de Unión al ADN
/
Macrófagos
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Blood
Año:
1998
Tipo del documento:
Article
País de afiliación:
Estados Unidos